Hot-air furnace.



No. 807,050. PATENTED DEC. 12, 1905. 0. W. SIRAN. HOT AIR FURNACE.

APPLICATION FILED MAR.26,1904.

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No. 807,050. PATENTED DEG. 12, 1905. I

G. W. STRAN.

HOT AIR FURNACE.

APPLICATION FILED MAR.26,1904. Y

4 sums-sum 2.

PATENTED DBO. 12, 1905.

0. W. STRAN.

HOT AIR FURNACE.

APPLICATION FILED MAR.26,1904.

4 SHEETSSHEET 3.

INVENTOH WITNESSES.

A; ATTORNEYS APPLICATION FILED MAR.26,1904.

4 SHEETSBHEET 4.

"INVENTOH W/ TNE SSE 8:

PATENT OFFICE.

CHARLES W. STRAN, OF CLEVELAND, OHIO.

1 HOT-AIR FURNACE.

Specification of Letters Patent.

Patented Dec. 12, 1905.

Application filed March 26, 1904. Serial No. 200,102.

T0 on whom it potty concern.-

Be it known that I, CHARLES W. STRAN, a citizen of the United States of America, residing at Cleveland, in the county of Ouyahoga and State of Ohio, have invented certain new and useful Improvements in Hot-Air Furnaces; andIhereby declare the following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which it pertains to make and use the same.

This invention relates to improvements in hot-air furnaces, and pertains more especially to a hot-air furnace in which either solid fuel such, for instance, as -coalor fluid fuelsuch, for instance, as inflammable gas or vaporcan be burned.

One object of this invention is to provide the fire-pot of the furnace at its upper end and exteriorly with an annularinteriorly-chambered enlargement, with the interior chamber of the said enlargement of the fire-pot in communication with a gas-supply pipe, with the inner side wall of the said chamber provided with downwardly and inwardly discharging orifices connecting the said chamber with the interior chamber of the fire-pot, and with inwardly and downwardly projecting deflectors integral with the fire-pot at the top of the discharging ends of the said orifices and instrumental in spreading the flame issuing from the said orifices during the operation of the furnace.

Another object is not only to effect the passage of air to be heated to and around the firepot and thence upwardly and over a domeshaped casting or section mounted upon the upper end of the fire-pot, but also through upwardly and inwardly extending ducts with which the said dome-shaped section isprovided and which overhang the interior chamber of the fire-pot and communicate, in common with an air-receiving chamber formed in and centrally of the top of the said domeshapedsection, over and centrally of the fire pot chamber, with the said air receiving chamber, placed in communication with the hot-air chamber above at different points.

Another object is to arrange a plurality of heating drums or radiators at diflerent elevations above the outlet of the aforesaid domeshaped section for the products of combustion ascending from the fire-pot chamber during the operation of the furnace and to conduct the said products of combustion successively through the different heating drums or radiators in the passage of the said products of combustion to the smoke-flue of the furnace.

Another object is to conduct the air to be heated upwardly to and around, in, under, and over the different heating drums or radiators, respectively, during the passage of the said air upwardly through the hot-air chamber of the furnace.

The primary object of this invention is to utilize the products of combustion advantageously, so as to effect great economy in the consumption of fuel.

With these objects in view and to the end of realizing other advantages hereinafter appearing this invention consists in certain features of construction and combinations and arrangement of parts hereinafter described, and pointed out in the claims.

In the accompanying drawings, Figure 1 is a side elevation, in central vertical section, of

a hot-air furnace embodying my invention. Fig. 2 is a top plan, in horizontal section, on line 2 2, Fig. 1. Fig. 3 is a side elevation in section on line 3 3, Fig. 1, looking in the direction indicated by the arrow. Figs. L and 5 are top plans, in horizontal section, on lines 4 4 and 5 5, respectively, Fig. 1.

Portions are broken away in Figs. 2 and 3 to more clearly show the construction.

Referring to the drawings, A (see Fig. 1) designates the ash-pit of the furnace, which ash-pit is formed by a suitably-shaped receptacle (0, arranged at the bottom and centrally of the furnace, and B designates a doorway communicating with the ash-pit and closed at its outer end by a suitably-applied door 5. A grate O is supported from the receptacle (0 and extends over the ash-pit. A fire-pot D is mounted upon the upper end of the receptacle a. The fire-pot D flares upwardly somewhat and' is provided at its upper end and exteriorly with an interiorly-chambered annular enlargement (Z, which extends circumferentially of the fire-pot. The interior chamber 10 of the enlargementd of the fire-pot D is annular, extending circumferentially of the fire-pot and communicating at one side of the fire-pot with the gas-supply pipe f. The chamber 10 is provided in its inner side wall with orifices 12, which are arranged at short intervals circumferentially of the fire-pot and communicate with the said chamber at the top of the chamber. The orifices 12 extend downwardly and inwardly from the chamber 10 and communicate at their lower ends with the interior chamber 13 of the fire-pot D. The

spectively. Obviously, therefore, any flames issuing from the orifices 12 are advantageously spread or distributed in heating the fire-pot D.

A dome-shaped section E is mounted upon the upper end of the fire-pot D and consists, preferably, of an iron casting. The upper portion of the dome-shaped section D is conical or gradually reduced transversely toward its upper end, as at 15. The outlet 16 in the dome E for the products of combustion arising within the fire-pot from the fuel burned within the said pot during the operation of the furnace is formed at the upper end and centrally of the upper conical portion 15 of the dome E and is flanged upwardly and annularly, as at 17. The domeE is provided at one side with a doorway'G, which is closed at its outer end by a suitably-applied door g. The section E is provided at the top and centrally of its outlet 16 with an air-receiving pocket or chamber 18, which is arranged at an elevation above the doorway G and centrally relative to the fire-pot. The chamber 18 is in communication with the upper ends of three ducts 20, which are also formed in the section E and extend upwardly and inwardly from the exterior and lower end of the said section to the upper end and centrally of the said section. The ducts 20 are arranged at suitable intervals circumferentially of the fire-pot D and communicate at their lower ends with the cold-air-receiving chamber H, which extends around the ash-pit-forming receptacle a and upwardly around the fire-pot D. The chamber H is provided at its lower end with air-inlets it, which communicate with the atmosphere exteriorly of the furnace. The air-chamber H is formed between the furnace-casing J and the ash-pit-forming receptacle a and the fire-pot D, the said casing being enough larger diametrically than the firepot to form the said chamber.

I would here remark that the chamber-18, as shown very clearly in Figs. 1, 2, and 3, is deepest where the ducts 2O connect therewith and is shallowest centrally and directly opposite the doorway G, so as to interfere as little as possible with the shoveling of solid fuel through the said doorway and into the firepot.

The provision of a single casting to form the dome E, the chamber 18, and the ducts 2O constitutes a feature of no inconsiderable importance. By this construction the fire-pot D and the dome or feed-section E are as readily assembled as would be the case if the chamber 18 and the ducts 20 were not provided. The ducts 20 are arranged wholly above the fire-pot. The air passing through the said ducts and the chamber 18 prevents overheating of the dome E, and joints to be rendered and kept fluid-tight at the ends of the said ducts are avoided.

The casing J extends upwardly a suitable distance above the dome E and above the said dome forms the hot-air chamber Iof the furnace. The casing J is provided at the top of the furnace with apertures 2', which form the air-outlets of the hot-air chamber and through which the hot-air is conducted to the place or places desired.

Three radiator-forming heating-drums L, P, and R are arranged within and centrally of the hot-air chamberI above the dome E, which drums are arranged at diiferent elevations, respectively. The lowermost drum L is annular and rests upon the upper conical portion 15 of the dome E and has its interior chamber Z communicating at the bottom and centrally with the outlet 16 of the interior chamber of the said dome. Preferably the interior chamber of the drum L is provided at the-bottom and centrally with a downwardly and annularly flanged inlet 23. The flange 2a, which extends around the-inlet 23, rests upon the conical portion 15 of the dome E.

The drum L extends over and is arranged a short distance above an annular conical deflector m, which is supported from the furnace-casing J in any approved manner and overhangs the conical upper portion 15 of the dome E, which deflector is enough larger diametrically than the said dome to form an annular space between the said dome and the said deflector, which space communicates at the upper end of the deflector with the hotair chamber I above and is in communication at the lower end of the deflector with the coldair chamber H below. The deflector m not only causes the air ascending through the cold-air chamber H to pass over the dome E, but prevents a straight upward passage of air, and being arranged above the air-receiving ends of the ducts 2O insures an adequate supply of air to the said ducts. I

The interior chamber Z of the drum L is provided, in the top wall thereof, with two upwardly and annularly flanged outlets 26, arranged, preferably, at opposite sides, respectively, of a vertically-arranged air-flue 27, with which the central or intermediate drum P is centrally provided. The flue 27 depends into the opening 28 centrally of the annular drum L. The opening 28 communicates at its lower end with the air-chamber l8 and is in communication at its upper end with the hot-air chamber 1. The flue 27 communicates at its lower end with the opening 28, and con- TIO . the drum L. The flanges 33, which are formed upon the drum P and extend around the inlets 32, are shown snugly embraced by the flanges 29, which are formed upon the drum L and extend around the outlets 26. The drum P is provided also with two interior passage-ways 34, which extend, as shown in Fig. 4, along the outer side of the different chambers 30, respectively. The passage-ways 34 communicate at one end with the different chambers 30, respectively, and are in communication at their other end with the inlet 32 of the different chambers 30, respectively.

The uppermost drum R is arranged a short distance above the intermediate drum P and extends over the upper end of the air-flue 27. The bottom of the drum R is provided with two downwardly and annularly flanged apertures 35, with the flanges 36, which extend around the said apertures, snugly fitting, as shown in Figs. 4 and 5, interiorly of the annular flanges 37, which are formed upon the drum P and extend around the aperture 38, formed in the top of the drum P. The apertures 35 and 38 establish communication between the chambers 30 of the drumP and two passage-ways 40, with which the drum R is interiorly provided. The passageways 40 are arranged at opposite sides, respectively,

By the construction hereinbefore described it will be observed that the lowermost drum L is supported at its depending annular flange 24 from the upper conical portion 15 of the dome E; that the intermediate drum P is mounted upon the flanges 29, formed upon the lowermost drum L around the outlets 26 of the interior chamber of the last-mentioned drum; that the uppermost drum R is mounted upon the flanges 37 formed upon the intermediate drnm P around the outlets 38 of the interior chambers of the said intermediate drum; that the products of combustion arising from the interior chamber of the fire-pot during the operation of the furnace pass through the outlet 16 of the dome E into the interior chamber Zof the lowermost drum L and fromwithin the said chamber at the outlets 26 of the said chamber into theinterior chambers 30 of the intermediate drumP and from the lastmentioned chambers at their outlets 38 into the passage-ways 40 of the uppermost drum Rand thence to the smoke-flue; that the cold air passing upwardly into the chamber H around the ash pit forming receptacle (0 and upwardly around the fire-pot D passes partially through theducts 20 of the domeE and through the chamber 18 and connected opening 28 into the hot-air chamber 1; that the intermediate drum P spreads the air passing in under the said drum from the opening 28 over the lowermost drum L; that air passes not only through the opening 28 around the air-flue 27, but also through the said flue into the chamber 42, which contains the uppermost drum R; that the air thus passing into the said chamber 42 is spread or distributed by the said drum R over the intermediate drum P and passes around and over the uppermost drum B through the outlet 43 of the chamber 42 into the hot-air chamber I, and that air passing from the exterior of the fire-pot and passing above the lower and air-receiving ends of the ducts 20 to and in under the deflector m is deflected inwardly by the said deflector over the conical portion 15 of the dome E and thence passes upwardly to and against the exterior of the bottom of the lowermost drum L and thence through the hotair chamber I. It will be observed, there- .fore, that by the construction bereinbefore described the products of combustion arising from fuel consumed within the combustionchamber 13 are utilized economically and that the air to be heated is so distributed during its upward passage relative to the heatradiating surfaces that the consumption of fuel required to adequately heat the air is reduced to a minimum.

What I claim is" 1. A hot-air furnace comprising a fire-pot; the hot-air chamber above; a dome mounted upon the fire-pot and provided at the top and centrally with an outlet; means for conducting products of combustion from the said outlet; the cold-air chamber arranged exteriorly of the fire-pot and extending upwardly next exteriorly of the dome and in communication with the atmosphere exterior'ly of the furnace; a plurality of ducts extending upwardly and inwardly from the exterior and lower end of the dome, which ducts communicate at their lower ends with the aforesaid cold-air chamher, and an air-chamber formed in and centrally of the top of the dome and open at the top, and the last-mentioned air-chamber being in communication with the aforesaid ducts and with the aforesaid hot-air chamber and arranged centrally of the aforesaid outlet so as to be exposed exteriorly to products of combustion ascending from the fire-pot.

2. -A hot-air furnace comprising a fire-pot; the hot-air chamber above; a dome mounted upon the fire-pot and consisting of a single casting provided at the top and centrally with an outlet for products of combustion arising from within the fire-pot; means for conducting products of combustion from the said outlet; the coldair chamber arranged exteriorly of the firepot and extending upwardly next exteriorly of the dome and in communication with the atmosphere exteriorly of the furnace; a plurality of ducts formed in the aforesaid casting and extending upwardly and inwardly from the exterior and lower end of the dome, which ducts are arranged wholly above the fire-pot and communicate at their lower ends with the aforesaid cold-air chamber, and an air-chamber formed in and centrally of the upper portion of the aforesaid casting and open at the top, and the last-mentioned air.

chamber being in communication with the aforesaid ducts and with the aforesaid hot-air chamber and arranged centrally of the'aforesaid outlet so as to be surrounded by products of combustion ascending from the fire-pot.

3. A hot-air furnace comprising a fire-pot; a dome mounted upon the fire-pot and provided, at the top, with an outlet for the products of combustion arising from within the fire-pot; a cold-air chamber arranged exteriorly of the fire-pot and dome and in communication with the atmosphere exteriorly of the furnace; a hot-air chamberabove the dome and provided with air-outlets; a radiatorforming interiorly-chambered heating-drum arranged above the dome and annular to form an opening arranged centrally of the drum, which opening is in communication, at its up: per end, with the hot-air chamber, and with the interior chamber of the drum provided, at the bottom and centrally, with an inlet communicating with the outlet of the dome; a plurality of ducts extending upwardly and inwardly from the exterior and lower end of the dome, which ducts communicate, at their upfurnace; a hot-air chamber above the dome and provided with air-outlets; a radiatorforming interiorly-chambered heating-drum arranged above the dome and annular to form an opening arranged centrally of the drum, which opening is in communication, at its upper end, with the hot-air chamber, and with the interior chamber of the drum provided, at the bottom and centrally, with an annularly and downwardly flanged inlet communicating with the outlet'of the dome, with the flange, which extends around the said inlet, resting upon the aforesaid conical portion of the dome; a plurality of ducts extending upwardly and inwardly from the exterior and lower end of the dome, which ducts communicate, at their upper ends, with the aforesaid opening and are in communication, at their lower ends,

with the cold-air chamber, and means for con-' ducting products of combustion from' the interior chamber of the drum.

5. A hot-air furnace comprising a fire-pot; a dome mounted upon the fire-pot and provided, at the top, with an outlet for the products of combustion arising from within the fire-pot, which dome has its upper portion conical; a cold-air chamber arranged exteriorly of the fire-pot and dome and in communication with the atmosphere exteriorly of the furnace; the hot-air chamber above; an annular conical deflector overhanging the aforesaid conical portion of the dome, which deflector is large enough diametrically to form an annular space between it and the dome, which space communicates, at the upper end of the deflector, with the hot-air chamber above and is in communication, at its lowerend, with the cold-air chamber below; a radiator-forming interiorly-chambered heating-drum arranged a suitable distance above and extending over the deflector, which drum is annular to form an opening arranged centrally of the said drum,which openingis in communication, at its upper end, with the hot-air chamber, and with the interior chamber of the drum provided, at the bottom and centrally, with an inlet communicating with the outlet of the dome; means for conducting air from the coldair chamber upwardly and inwardly to the aforesaid opening, and means for conducting products of combustion from the interior chamber of the drum.

6. A hot-air furnace comprisinga fire-pot; a dome mounted upon the fire-.pot and provided, at the top, with an outlet for the products of combustion arising from within the fire-pot; the furnace-casing extending around the fire-pot and dome and large enough in dimensions to form the hot-air chamber above and the cold-air chamber below, with the latter arranged exteriorly of the fire-pot and dome and in communication with the atmosphere exteriorly of the furnace; an annular conical deflector supported from the furnacecasing and overhanging the upper portion of the dome, which deflector is large enough diametrically to form an annular space between it and the dome, which space communicates, at the upper end of the deflector, with the hot-air chamber above and is in communication, at its lower end, with the cold-air chamber below; a radiator-forming interiorly-chambered heating-drum arranged a suitable distance above and extending over the deflector, which drum is annular to form an opening arranged centrally of the drum, which opening is in communication, at its upper end, with the hot-air chamber and with the interior chamber of the drum provided, at the bottom and centrally, with an inlet communicating with the outlet of the dome; several upwardly andinwardly extendingducts arranged at suitable intervals around the dome and communicating, at their upper ends, with the aforesaid opening, which ducts are in communication, at their lower ends and below the aforesaid deflector, with the coldair chamber, and means for conducting products of combustion from the interior chamber of the drum.

7. A hot-air furnace comprising a fire-pot;

the cold-air chamber arranged exteriorly of the fire-pot and in communication with the atmosphere exteriorly of the furnace; the hotair chamber above; a radiator-forming interiorly-chambered heating-drum provided, at the bottom, with an inlet communicating with the interior chamber of the fire-pot; a smokeflue in communication with the interior chamber of the drum; several ducts extending upwardly and inwardly over the fire-pot and in communication, at their upper ends, with the hot-air chamber and communicating, at their lower ends, with the aforesaid cold-air chamber, and means for guiding air ascending next exteriorly of the fire-pot into the said ducts.

8. A hot-air furnace comprising a fire-pot; a cold-air chamber arranged exteriorly of the fire-pot and in communication with the at mosphere exteriorly of the furnace; the hotair chamber above; a radiator-forming interiorly-chambered. heating-drum arranged a suitable distance above the fire-pot, and annular to form an opening arranged centrally of the drum, which opening is in communication, at its upper end, with the hot-air chamber, and with the interior chamber of the drum provided, at the bottom and centrally,

with an inlet in communication with the interior chamber of the fire-pot; a plurality of upwardly and inwardly extending ducts communicating, at their upper ends, with the aforesaid opening and in communication, at their lower ends, with the cold-air chamber, and means for conducting products of combustion from the interior chamber of the nular to form an opening arranged centrally of the drum, which opening is in communication, at its upper end, with the hot-air chamber, and with the interior chamber of the drum provided, at the bottom and centrally, with an inlet which is in communication with the interior chamber of thefire-pot; a plurality of upwardly and inwardly extending ducts communicating, at their upper ends, with the aforesaid opening and in communication, at their lower ends, with the cold-air chamber; another radiator-forming interiorly-chambered heating-drum arranged a suitable distance above the aforesaid annular drum and provided centrally with an upright air-flue and having its interior in communication with the interior chamber of the aforesaid annular drum, said air-flue being in communication, at its upper end, with the hot-air chamber and communicating, at its lower end, with the aforesaid ducts, and means for conducting products of combustion from the interior chamber of the upper drum.

10. A hot-air furnace comprising a fire-pot; a dome mounted upon the fire-pot and provided with an outlet for the products of combustion arising from within the fire-pot; the furnace-casing extending around the fire-pot and dome and large enough in dimensions to form the hot-air chamber above and the cold-air chamber below, with the latter arranged exteriorly of the fire-pot and dome and in communication with the atmosphere exteriorly of the furnace; a suitably-supported deflector overhanging the upper portion of the dome, which deflector is arranged to form a space between it and the dome, which space communicates with the hot-air chamber and with the cold-air chamber; a radiator-forming interiorly-chambered heating-drum arranged a suitable distance above and extending over the deflector and having an interior chamber communicating with the outlet of the dome, which drum is shaped to form an opening which is arranged centrally of the drum and communicates with the hot-air chamber; several upwardly and inwardly extending ducts arranged at suitable intervals around the dome and communicating at their upper ends with the aforesaid opening, which ducts are in communication at their lower ends and in under the aforesaid deflector with the coldair chamber, and means for conducting products ofcombustion from the interior chamber of the drum. Y

11. A hot-air furnace comprising afire-pot; a dome mounted upon the fire-pot and provided with an outlet for the products of combustion arising from within the fire-pot; the furnace-casing extending around the fire-pot and dome and large enough in dimensions to form the hot-air chamber above and the coldair chamber below, with the latter arranged exteriorly of the fire-pot and dome and in communication with the atmosphere exte- IIO riorly of the furnace; a suitably-supported deflector overhanging the upper portion of the dome, which deflector is arranged to form a space between it and the dome, which space communicates with the hot-air chamber and with the cold-air chamber; several upwardly and inwardly extending ducts arranged at suitable intervals around the dome and in communication at their upper ends with the hot-air chamber, which ducts are in communication at their lower ends and in under the aforesaid deflector with the cold-air chamber, and means for conducting products of combustion from the outlet of the dome.

12. A hot-air furnace comprising a fire-pot; a dome mounted upon the fire-pot and provided with an outlet for the products of combustion arising from within the fire-pot; the furnace-casing extending around the fire-pot and dome and large enough in dimensions to form the hot-air chamber above and the coldair chamber below, with the latter arranged exteriorly of the tire-pot and dome and in communication with the atmosphere exteriorly of the furnace; a deflector supported from the furnace-casing and extending around and overhanging the upper port-ion of the dome, which deflector is arranged to form a space between it and the dome, which space communicates with the hot-air chamber and with the cold-air chamber; a radiator-forming interiorly-chambered heating-drum arranged a suitable distance above and extending over the deflector, which drum is shaped to form an opening centrally of the drum, with the said opening in communication with the hot-air chamber, and with the interior chamber of the drum in communication with the outlet of the dome; several upwardly and inwardly extending ducts arranged at suitable intervals around the dome and communicating, at their upper ends, with the aforesaid opening, which ducts are in communication, at their lower ends and below the aforesaid deflector, with the cold-air chamber, and means for conducting products of combustion from the interior chamber of the drum.

13. A hot-air furnace comprising a fire-pot; a dome mounted upon the [ire-pot and having an upper conical portion provided with an outlet for the products of combustion arising from within the fire-pot; means for conducting products of combustion from the said outlet; the furnace-casing extending. around the fire-pot and dome and large enough in dimensions to form the hot-air chamber above and the cold-air chamber below, with the latter arranged exteriorly of the fire-pot and dome and in communication with the atmosphere exteriorly of the furnace; a deflector supported from the furnace-casing andextending around and overhanging the aforesaid conical portion of the dome, which deflector is large enough diametrically and arranged to form a space between it and the dome, which the fire-pot; means for conducting products of combustion from the said outlet; the coldair chamber arranged exteriorly of the firepot and extending upwardly next exteriorly of the dome and in communication with the atmosphere exteriorly of the furnace; a plurality of ducts extending upwardly and inwardly from the exterior and lower end of the dome, which ducts communicate, at their lower ends and above the fire-pot, with the aforesaid cold-air chamber; an air-chamber arranged centrally of and formed in the upper portion of the dome and in communication with the said ducts and with the afore said hot-air chamber, and a deflector overhanging the dome and arranged to form a space between the deflector and the dome above the lower and air-receiving ends of the aforesaid ducts.

15. A hot-air furnace comprising a fire-pot; the hot-air chamber above; a dome mounted upon the fire-pot and consisting of a single casting, which dome is provided with an outlet for products of combustion arising from within the fire pot; means for conducting products of combustion from the said outlet; the cold-air chamber arranged exteriorly of the fire-pot and extending upwardly next exteriorly of the dome and in communication with the atmosphere exteriorly of the furnace, and several ducts formed in the aforesaid casting and extending upwardly and inwardly from the exterior and lower end of the dome, which ducts communicate, at their lower ends, with the aforesaid cold-air chamber, and are in communication, at their upper ends, with the aforesaid hot-air chamber; a'deflector overhanging and extending around the aforesaid casting and arranged to form a space between the deflector and the casting above the lower and air receiving ends of the aforesaid ducts.

16. A hot-air furnace comprising a fire-pot; the hot-air chamber above; a dome mounted upon the fire-pot and comprising a casting provided at the top of the dome with an out let for products of combustion arising from within the fire-pot, which dome is provided at the front of the furnace with an inlet; means for conducting products of combustion from the aforesaid outlet; the cold-air chamber arranged exteriorly of the fire-pot and extending upwardly next exteriorly of the dome and in communication with the atmosphere v exteriorly of the furnace; a plurality of ducts formed in the aforesaid casting at suitable intervals round the dome rearward of the aforesaid inlet and extending upwardly and inwardly from-the exterior and lower end of the dome, which ducts communicate, at their lower ends, with the aforesaid cold-air chamber, and an air-chamber formed in and centrally of the upper portion of the aforesaid casting and open at the top, and the last-mentioned airchamber being in communication with the aforesaid ducts and with the aforesaid hot-air chamber and decreasing in depth in the direction of the aforesaid inlet.

17. A hot-air furnace comprising a fire-pot; a dome mounted upon the fire-pot and provided at the top with an outlet for the products vof combustion arising from within the fire-pot, which dome has its upper portion conical; a cold-air chamber'arranged exteriorly of the fire-pot and dome and in communication with the atmosphere exteriorly of the furnace; a hot-air chamber above the dome;

mentioned chamber and are in communication, at their lower ends, with the aforesaid. coldair chamber, and means for conducting products of combustion from the interior chamber of the drum. 7

In testimony whereof I sign the foregoing specification, in the presence of two witnesses, this 23d day of March, 1904-, at Cleveland,

Ohio.

CHARLES W. STRAN. Witnesses:

C. H. DORER, B. 0. BROWN.

municate, at their upper ends, with the last- 

